Vitamin D pills may protect against colds and flu

People who have low levels of vitamin D may catch fewer colds, flu and other respiratory infections if they take a supplement, say scientists from Queen Mary University of London.

Their study – published in the British Medical Journal – is believed to offer the most convincing evidence yet that vitamin D has benefits beyond boosting bone and muscle health. It follows advice from Public Health England that suggests everyone in the UK should consider taking a daily 10mcg vitamin D supplement during the autumn and winter, when sunshine is in short supply (vitamin D is produced in the body when skin is exposed to sunlight). (See Vitamin D supplements for all).

“This major collaborative research effort has yielded the first definitive evidence that vitamin D really does protect against respiratory infections,” says lead researcher Professor Adrian Martineau.

Vitamin D is thought to protect against respiratory infections by boosting levels of antimicrobial peptides – natural antibiotic-like substances – in the lungs. The study’s findings may also explain why colds and flu are more common during the winter and spring, as this is when levels of vitamin D are at their lowest. It may also shed some light on why vitamin D may protect against asthma attacks, which are commonly triggered by respiratory viruses.

Worldwide trial

Almost 11,000 people were involved in the trial, which was conducted in 14 countries including the UK, USA, Japan, India, Afghanistan, Belgium, Italy, Australia and Canada. Daily or weekly supplementation with vitamin D was found to halve the risk of acute respiratory infection in people with the lowest vitamin D levels. People with higher levels also benefitted from a more modest risk reduction (10 percent).

“The bottom line is that the protective effects of vitamin D supplementation are strongest in those who have the lowest vitamin D levels, and when supplementation is given daily or weekly rather than in more widely spaced doses,” says Professor Martineau.

“Vitamin D fortification of foods provides a steady, low-level intake of vitamin D that has virtually eliminated profound vitamin D deficiency in several countries. By demonstrating this new benefits of vitamin D, our study strengthens the case for introduction food fortification to improve vitamin D levels in countries such as the UK, where profound vitamin D deficiency is common.”

Are you at risk?

Public Health England now advises adults and children over the age of one to consider taking a daily 10mcg supplement of vitamin D, particularly during autumn and winter. Those who have a higher risk of vitamin D deficiency – such as people who get little or no sun exposure (including those who cover their skin when they’re outside) and people with dark skin – are also advised to take a supplement all year round.

If you’re considering taking a vitamin D supplement, why not have a chat with your local Careway pharmacist about it? Your pharmacist can advise whether or not you’re at risk of having low vitamin D levels, and recommend a supplement that would suit you.

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